Light-importing system, direct-lit backlight module and liquid crystal display device

ABSTRACT

The present invention provides a light-importing system, direct-lit backlight module and liquid crystal display device. The light-importing system includes ambient light collection system, facing and collecting ambient light, and outputting absorbed light; a plurality of light-guiding devices, each having light-entering end and light-exiting end, light-entering end adjacent to ambient light collection system, the absorbed light entering light-entering end and guided to light-exiting end, the plurality of the light-exiting ends being arranged in an array format underneath a light-entering surface of a diffuser; and a plurality of light diffusion devices, each disposed between light-exiting end and light-entering surface, expanding the light-emitting angle of the light-exiting end. Because of light diffusion device disposed between light-exiting end and light-entering surface expanding light-emitting angle of light-exiting end, the phenomenon of uneven luminance between light-exiting ends is improved, leading to improvement of displaying quality of direct-lit backlight module.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of liquid crystal displayingtechniques, and in particular to a light-importing system, direct-litbacklight module and liquid crystal display device.

2. The Related Arts

Recently, the backlight module of the liquid crystal display device usesmostly original light source as the backlight source. The original lightsource means the light source using electricity to emit light, such as,LED, and CCFL. The LED has the advantage of high energy efficiency, andis widely used as the backlight source in backlight modules. However, asthe demands on even higher efficiency in energy consumption grow, thenumber of original light sources in the backlight module must be reducedto meet such a high standard. Alternatively, a new type of energy-savinglight source must be developed as the backlight module to meet thedemands.

By using the ambient light, such as, sun light, as the backlight sourcein the backlight module is a new energy-saving approach. In thisapproach, the original light source relying on electricity is reduced oreven eliminated to save the energy consumption. At present, a possiblyfeasible approach is to collect the ambient light and use a plurality ofoptical fibers to output the collected ambient light to the backlightmodule to serve as the backlight source of the backlight module.However, because the light-emitting angle at the light-exiting end issmaller, the luminance difference between the light-exit end and thefront of the light-exiting end (i.e., between left and right of thelight-exiting end) is large, which leads to distinct luminancedifference. An even more severe case would show the distinct locationsof each light-exiting end, which results in deterioration of thedisplaying quality.

SUMMARY OF THE INVENTION

The present invention provides a light-importing system, applicable todirect-lit backlight module, which comprises: an ambient lightcollection system, configured to face the ambient light to absorb theambient light and output the absorbed light; a plurality oflight-guiding devices, each having a light-entering end and alight-exiting end, the light-entering end being adjacent to the ambientlight collection system, the absorbed light entering the light-enteringend and being guided to the light-exiting end, the plurality of thelight-exiting ends being arranged in an array format underneath alight-entering surface of a diffuser; and a plurality of light diffusiondevices, each disposed between the light-exiting end and thelight-entering surface, configured to expand the light-emitting angle ofthe light-exiting end.

The present invention provides a direct-lit backlight module, whichcomprises: a backplane, a reflector, a diffuser and an optical film;wherein the diffuser having a light-entering surface and a light-exitingsurface, disposed oppositely; the reflector being disposed underneaththe light-entering surface, the backplane being disposed underneath thereflector; the optical film being disposed above the light-exitingsurface; wherein the direct-lit backlight module further comprising alight-importing system, the light-importing system, comprising: anambient light collection system, configured to face the ambient light toabsorb the ambient light and output the absorbed light; a plurality oflight-guiding devices, each having a light-entering end and alight-exiting end, the light-entering end being adjacent to the ambientlight collection system, the absorbed light entering the light-enteringend and being guided to the light-exiting end, the plurality of thelight-exiting ends being arranged in an array format underneath alight-entering surface of a diffuser; and a plurality of light diffusiondevices, each disposed between the light-exiting end and thelight-entering surface, configured to expand the light-emitting angle ofthe light-exiting end.

The present invention provides a liquid crystal display device, whichcomprises: which comprises: a backplane, a reflector, a diffuser, anoptical film and a display panel; wherein the diffuser having alight-entering surface and a light-exiting surface, disposed oppositely;the reflector being disposed underneath the light-entering surface, thebackplane being disposed underneath the reflector; the optical filmbeing disposed above the light-exiting surface; the display panel beingdisposed above the optical film; wherein the liquid crystal displaydevice further comprising a light-importing system, the light-importingsystem, comprising: an ambient light collection system, configured toface the ambient light to absorb the ambient light and output theabsorbed light; a plurality of light-guiding devices, each having alight-entering end and a light-exiting end, the light-entering end beingadjacent to the ambient light collection system, the absorbed lightentering the light-entering end and being guided to the light-exitingend, the plurality of the light-exiting ends being arranged in an arrayformat underneath a light-entering surface of a diffuser; and aplurality of light diffusion devices, each disposed between thelight-exiting end and the light-entering surface, configured to expandthe light-emitting angle of the light-exiting end.

According to a preferred embodiment of the present invention, thelight-guiding device is optical fiber.

According to a preferred embodiment of the present invention, the lightdiffusion device is a biconcave lens or a plano-concave lens.

According to a preferred embodiment of the present invention, thelight-exiting end is corresponding to the center of the light diffusiondevice, and the light diffusion device has a width meeting the followingcondition: W<P, wherein W is the width of the light diffusion device andP is the distance between two adjacent light-exiting ends.

According to a preferred embodiment of the present invention, thelight-importing system further comprises a plurality of original lightsources, and the plurality of original light sources and the pluralitylight-exiting ends are arranged interleavingly in an array format.

According to a preferred embodiment of the present invention, theoriginal light source is an LED.

According to a preferred embodiment of the present invention, thelight-exiting end is corresponding to the center of the light diffusiondevice, and the light diffusion device has a width meeting the followingcondition: W<P₂−L and W<P₁−L, wherein W is the width of the lightdiffusion device, P₁ is the distance between two adjacent light-exitingends, P₂ is the distance between two adjacent original light sources andL is the width of the original light source.

The efficacy of the present invention is that to be distinguished fromthe state of the art. According to the light-importing system,direct-lit backlight module and the liquid crystal display device of thepresent invention, the light-importing system imports the ambient lightinto the direct-lit backlight module to serve as the backlight source ofthe backlight module to reduce or eliminate the use of the originallight source and save energy consumption. In addition, because of thelight diffusion device disposed between the light-exiting end and thelight-entering surface to expand the light-emitting angle of thelight-exiting end, the phenomenon of uneven luminance between thelight-exiting ends is improved, leading to improvement of displayingquality of direct-lit backlight module.

BRIEF DESCRIPTION OF THE DRAWINGS

To make the technical solution of the embodiments according to thepresent invention, a brief description of the drawings that arenecessary for the illustration of the embodiments will be given asfollows. Apparently, the drawings described below show only exampleembodiments of the present invention and for those having ordinaryskills in the art, other drawings may be easily obtained from thesedrawings without paying any creative effort. In the drawings:

FIG. 1 is a schematic view showing the structure of a direct-litbacklight module of the first embodiment of the present invention;

FIG. 2 is a schematic view showing the biconcave lens expanding thelight-emitting angle of the light-exiting end in the first embodiment ofthe present invention;

FIG. 3 is a schematic view showing the plano-concave lens expanding thelight-emitting angle of the light-exiting end in the first embodiment ofthe present invention;

FIG. 4 is a schematic view showing another disposition of theplano-concave lens of the first embodiment of the present invention;

FIG. 5 a schematic view showing the structure of a direct-lit backlightmodule of the second embodiment of the present invention; and

FIG. 6 is a schematic view showing the liquid crystal display device ofthe first embodiment or the second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

For description of the technical means and result of the presentinvention, the following refers to the drawings and embodiments fordetailed description, wherein the same number indicates the same part.

The First Embodiment

Referring to FIG. 1, the direct-lit backlight module 1 comprises: anambient light collection system 10, a plurality of optical fibers 20, aplurality of biconcave lenses 40, a backplane 50, a diffuser 30, anoptical film 60 and a reflector 90; wherein the diffuser 30 comprises alight-entering surface 31 and a light-exiting surface 32, disposedoppositely; the reflector 90 is disposed underneath the light-enteringsurface 31, the backplane is disposed underneath the reflector 90, andthe optical film 60 is disposed above the light-exiting surface 32.

In the instant embodiment, the ambient light collection system 10, theplurality of optical fibers 20 and the plurality of biconcave lenses 40form a light-importing system, wherein each optical fiber has alight-exiting end 21 and a light-entering end 22. The light-enteringends 22 of the plurality of optical fibers 20 are bundled together andplaced adjacent to the ambient light collection system 10. Thelight-exiting ends 21 of optical fibers 20 are arranged in an arrayformat above the reflector 90. In other words, the light-exiting ends 21of optical fibers 20 are arranged in an array format underneath thelight-entering surface 31. Each biconcave lens 40 is disposedcorrespondingly between the light-exiting end 21 of the optical fiber 20and the light-entering surface 31.

The ambient light collection system 10 faces the ambient light CL toabsorb the ambient light CL and transform the ambient light CL intoabsorbed light SL to output. The ambient light CL can be sun light, lamplight or light from any light-emitting objects. The wavelength of theabsorbed light SL is within the range of the visible light. In otherwords, the absorbed light SL can be used as backlight source for thebacklight module. The absorbed light SL passes the light-entering end 22to enter the optical fiber 20 and is propagated to the light-exiting end21. The light exiting the light-exiting end 21 passes the biconcave lens40 and the light-entering surface 31 to enter the diffuser 30. Thediffuser 30 diffuses the entering light and the diffused light isemitted from the light-exiting surface 32. In the instant embodiment,the optical fiber 20 is a preferred light-guiding device, and the lossin the optical fiber 20 is very low to ensure sufficient light reachingthe light-exiting end 21. As a light diffusion device, the biconcavelens 40 can expand the light-emitting angle of the light-exiting end.

In the instant embodiment, for the light-emitting angle of thelight-exiting end to be expanded to an maximum, the light-exiting end 21is preferably disposed correspondingly to the center of the biconcavelens 40 and maintains a suitable distance from the biconcave lens 40.The light emitted from the light-exiting end 21 passes the biconcavelens 40 to reach the light-entering surface. To minimize the unevenluminance phenomenon of the light-entering surface, the width of thebiconcave lens 40 must satisfy the following equation (1):

W<P  (1)

-   -   wherein W is the width of the biconcave lens 40, and P is the        distance between two adjacent light-exiting ends.

The following describes the theory behind the biconcave lens 40expanding the light-emitting angle of the light-exiting end in details.

Also referring to FIG. 2, for any two rays 211, 212 of the light emittedfrom the light-exiting end 21, assume that the biconcave lens 40 is notdisposed between the light-exiting end 21 and light-entering surface 31.The rays 211, 212 will travel along a straight line, i.e., the dash linein the figure, to form a light-emitting angle of M. However, as thebiconcave lens 40 is disposed between the light-exiting end 21 andlight-entering surface 31 in the present embodiment, the refractionoccurs the interface between any concave surface of the biconcave lens40 and the air for rays 211, 212. This is caused by the refraction indexof the biconcave lens 40 greater than the refraction index of the air,i.e., the rays 211, 212 will travel along the solid line in the figure.The dash line extending from the reverse direction of the solid line ofthe biconcave lens 40 forms a light-emitting angle of N. As shown, thelight-emitting angle N is greater than the light-emitting angle M.Similarly, any other rays emitted from the light-exiting end 21 followsthe same theory so that the light emitted from the light-exiting end 21after the biconcave lens 40 is expanded.

A plano-concave lens 41 can also be used to replace the biconcave lens40. The theory behind the plano-concave lens 41 expanding thelight-emitting angle of the light-exiting end 21 is described asfollows.

Referring to FIG. 3, the concave surface of the plane-concave lens 41 iscorresponding to the light-exiting end 21. For any two rays 211, 212 ofthe light emitted from the light-exiting end 21, assume that theplano-concave lens 41 is not disposed between the light-exiting end 21and light-entering surface 31. The rays 211, 212 will travel along astraight line, i.e., the dash line in the figure, to form alight-emitting angle of Q. However, as the plano-concave lens 41 isdisposed between the light-exiting end 21 and light-entering surface 31in the present embodiment, the refraction occurs the interface betweenthe concave surface or the planar surface of the plano-concave lens 41and the air for rays 211, 212. This is caused by the refraction index ofthe plano-concave lens 41 greater than the refraction index of the air,i.e., the rays 211, 212 will travel along the solid line in the figure.The dash line extending from the reverse direction of the solid line ofthe plano-concave lens 41 forms a light-emitting angle of K. As shown,the light-emitting angle K is greater than the light-emitting angle Q.Similarly, any other rays emitted from the light-exiting end 21 followsthe same theory so that the light emitted from the light-exiting end 21after the plano-concave lens 41 is expanded.

Referring to FIG. 4, the planar surface of the plano-concave lens 41 canalso be corresponding to the light-exiting end 21. The rays 211, 212will be refracted first at the interface between the air and the planarsurface of the plano-concave lens 41 and then refracted again at theinterface between the air and the concave surface of the plano-concavelens 41. As shown, the light-emitting angle K is greater than thelight-emitting angle Q, and the light emitted from the light-exiting end21 after the plano-concave lens 41 is expanded.

The Second Embodiment

The part of the description of the second embodiment that is identicalto the description of the first embodiment will not be repeated here.The following only describes different part.

LED is often used as an original light source of the backlight module.Other original light sources include fluorescent light, CCFL or otherlight-emitting objects with electricity as power.

Referring to FIG. 5, the direct-lit backlight module 1 can furthercomprise a plurality of LEDs 70. The LEDs 70 and the light-exiting ends21 are arranged interleavingly in an array format above the reflector90. That is, the LEDs 70 and the light-exiting ends 21 are arrangedinterleavingly in an array format underneath the light-entering surface31. The biconcave lens 40 is disposed between the light-exiting end 21and the light-entering surface 31. Alternatively, the plano-concave lens41 can be used instead of biconcave lens 40. With such structure, theLED 70 and the light-exiting ends 21 are used as the backlight source toreduce the number of LEDs used. In the present embodiment, the ambientlight collection system 10, the plurality of optical fibers 20, theplurality of LEDs 70 and the plurality of biconcave lens 40 form thelight-importing system.

It should be noted that in the instant embodiment, for thelight-emitting angle of the light-exiting end to be expanded to anmaximum, the light-exiting end 21 is preferably disposed correspondinglyto the center of the biconcave lens 40 and maintains a suitable distancefrom the biconcave lens 40. The light emitted from the light-exiting end21 passes the biconcave lens 40 to reach the light-entering surface. Tominimize the uneven luminance phenomenon of the light-entering surface,the width of the biconcave lens 40 must satisfy the following equation(2):

W<P ₂ −L and W<P ₁ −L  (2)

-   -   wherein W is the width of the biconcave lens 40, P₁ is the        distance between two adjacent light-exiting ends, P₂ is the        distance between two adjacent LEDs 70 and L is the width of the        LED 70.

The direct-lit backlight module of the first or second embodiment isapplicable to liquid crystal display device. The following describes aliquid crystal display device using the direct-lit backlight module ofthe first or second embodiment.

Referring to FIG. 6, a display panel 80 is disposed on the direct-litbacklight module 1 to form a complete liquid crystal display device 2.The direct-lit backlight module 1 provides uniformly distributed lightsource to the display panel 80 so that the display panel 80 hassufficient luminance to display images.

In summary, the light-importing system imports the ambient light intothe direct-lit backlight module to serve as backlight source to reduceor eliminate the use of original light source and save energy. Inaddition, the disposition of the biconcave lens or the plano-concavelens between the light-exiting end and the light-entering surface toexpand the light-emitting angle will improve the uneven luminancephenomenon between light-exiting ends and improve the displaying qualityof the direct-lit backlight module.

Embodiments of the present invention have been described, but notintending to impose any unduly constraint to the appended claims. Anymodification of equivalent structure or equivalent process madeaccording to the disclosure and drawings of the present invention, orany application thereof, directly or indirectly, to other related fieldsof technique, is considered encompassed in the scope of protectiondefined by the clams of the present invention.

What is claimed is:
 1. A light-importing system, applicable todirect-lit backlight module, which comprises: an ambient lightcollection system, configured to face the ambient light to absorb theambient light and output the absorbed light; a plurality oflight-guiding devices, each having a light-entering end and alight-exiting end, the light-entering end being adjacent to the ambientlight collection system, the absorbed light entering the light-enteringend and being guided to the light-exiting end, the plurality of thelight-exiting ends being arranged in an array format underneath alight-entering surface of a diffuser; and a plurality of light diffusiondevices, each disposed between the light-exiting end and thelight-entering surface, configured to expand the light-emitting angle ofthe light-exiting end.
 2. The light-importing system as claimed in claim1, wherein the light-guiding device is optical fiber.
 3. Thelight-importing system as claimed in claim 1, wherein the lightdiffusion device is a biconcave lens.
 4. The light-importing system asclaimed in claim 1, wherein the light diffusion device is aplano-concave lens.
 5. The light-importing system as claimed in claim 1,wherein the light-exiting end is corresponding to the center of thelight diffusion device, and the light diffusion device has a widthmeeting the following condition:W<P, wherein W is the width of the light diffusion device and P is thedistance between two adjacent light-exiting ends.
 6. The light-importingsystem as claimed in claim 1, wherein the light-importing system furthercomprises a plurality of original light sources, and the plurality oforiginal light sources and the plurality light-exiting ends are arrangedinterleavingly in an array format.
 7. The light-importing system asclaimed in claim 6, wherein the original light source is an LED.
 8. Thelight-importing system as claimed in claim 6, wherein the light-exitingend is corresponding to the center of the light diffusion device, andthe light diffusion device has a width meeting the following condition:W<P ₂ −L and W<P ₁ −L, wherein W is the width of the light diffusiondevice, P₁ is the distance between two adjacent light-exiting ends, P₂is the distance between two adjacent original light sources and L is thewidth of the original light source.
 9. A direct-lit backlight module,which comprises: a backplane, a reflector, a diffuser and an opticalfilm; wherein the diffuser having a light-entering surface and alight-exiting surface, disposed oppositely; the reflector being disposedunderneath the light-entering surface, the backplane being disposedunderneath the reflector; the optical film being disposed above thelight-exiting surface; wherein the direct-lit backlight module furthercomprising a light-importing system, the light-importing systemcomprising: an ambient light collection system, configured to face theambient light to absorb the ambient light and output the absorbed light;a plurality of light-guiding devices, each having a light-entering endand a light-exiting end, the light-entering end being adjacent to theambient light collection system, the absorbed light entering thelight-entering end and being guided to the light-exiting end, theplurality of the light-exiting ends being arranged in an array formatunderneath a light-entering surface of a diffuser; and a plurality oflight diffusion devices, each disposed between the light-exiting end andthe light-entering surface, configured to expand the light-emittingangle of the light-exiting end.
 10. The direct-lit backlight module asclaimed in claim 9, wherein the light-guiding device is optical fiberand the light diffusion device is a biconcave lens.
 11. The direct-litbacklight module as claimed in claim 9, wherein the light-guiding deviceis optical fiber and the light diffusion device is a plano-concave lens.12. The direct-lit backlight module as claimed in claim 9, wherein thelight-exiting end is corresponding to the center of the light diffusiondevice, and the light diffusion device has a width meeting the followingcondition:W<P, wherein W is the width of the light diffusion device and P is thedistance between two adjacent light-exiting ends.
 13. The direct-litbacklight module as claimed in claim 9, wherein the light-importingsystem further comprises a plurality of original light sources, and theplurality of original light sources and the plurality light-exiting endsare arranged interleavingly in an array format.
 14. The direct-litbacklight module as claimed in claim 13, wherein the light-exiting endis corresponding to the center of the light diffusion device, and thelight diffusion device has a width meeting the following condition:W<P ₂ −L and W<P₁ −L, wherein W is the width of the light diffusiondevice, P₁ is the distance between two adjacent light-exiting ends, P₂is the distance between two adjacent original light sources and L is thewidth of the original light source.
 15. A liquid crystal display device,which comprises: which comprises: a backplane, a reflector, a diffuser,an optical film and a display panel; wherein the diffuser having alight-entering surface and a light-exiting surface, disposed oppositely;the reflector being disposed underneath the light-entering surface, thebackplane being disposed underneath the reflector; the optical filmbeing disposed above the light-exiting surface; the display panel beingdisposed above the optical film; wherein the liquid crystal displaydevice further comprising a light-importing system, the light-importingsystem comprising: an ambient light collection system, configured toface the ambient light to absorb the ambient light and output theabsorbed light; a plurality of light-guiding devices, each having alight-entering end and a light-exiting end, the light-entering end beingadjacent to the ambient light collection system, the absorbed lightentering the light-entering end and being guided to the light-exitingend, the plurality of the light-exiting ends being arranged in an arrayformat underneath a light-entering surface of a diffuser; and aplurality of light diffusion devices, each disposed between thelight-exiting end and the light-entering surface, configured to expandthe light-emitting angle of the light-exiting end.
 16. The liquidcrystal display device as claimed in claim 15, wherein the light-guidingdevice is optical fiber and the light diffusion device is a biconcavelens.
 17. The liquid crystal display device as claimed in claim 15,wherein the light-guiding device is optical fiber and the lightdiffusion device is a plano-concave lens.
 18. The liquid crystal displaydevice as claimed in claim 15, wherein the light-exiting end iscorresponding to the center of the light diffusion device, and the lightdiffusion device has a width meeting the following condition:W<P, wherein W is the width of the light diffusion device and P is thedistance between two adjacent light-exiting ends.
 19. The liquid crystaldisplay device as claimed in claim 15, wherein the light-importingsystem further comprises a plurality of original light sources, and theplurality of original light sources and the plurality light-exiting endsare arranged interleavingly in an array format.
 20. The liquid crystaldisplay device as claimed in claim 19, wherein the light-exiting end iscorresponding to the center of the light diffusion device, and the lightdiffusion device has a width meeting the following condition:W<P ₂ −L and W<P ₁ −L, wherein W is the width of the light diffusiondevice, P₁ is the distance between two adjacent light-exiting ends, P₂is the distance between two adjacent original light sources and L is thewidth of the original light source.